Rash

A rash is a visible change in the skin that may involve color, texture, or elevation. Rashes are common and can be localized or widespread. They may itch, burn, sting, swell, or be tender. Rashes result from inflammation due to infection, allergy, irritation, or autoimmune processes, and may present as red patches, bumps, scales, vesicles, or crusting.

Common causes include contact dermatitis from soaps or metals, atopic dermatitis, fungal or bacterial infections, viral exanthems, drug reactions, heat rash, and conditions such as psoriasis or hives. Rashes may accompany other symptoms such as fever, fatigue, cough, or swollen lymph nodes, depending on the underlying condition.

Evaluation is usually clinical and based on history and exam. Tests such as skin swabs, patch testing, blood tests, or skin biopsy may be used when the cause is unclear. Treatments target the cause: emollients and moisturizers to restore the skin barrier; topical steroids or calcineurin inhibitors for inflammation; antihistamines for itch.

Prognosis varies; many rashes resolve with simple measures in days to weeks, but some are chronic or recurrent. Prevention focuses on trigger avoidance and skin care. Seek medical care for rapidly spreading rashes, those with fever, difficulty breathing, severe pain, signs of infection, or in people with weakened immune systems.